Risk of Thyroid Tumors With GLP-1 Receptor Agonists: A Retrospective Cohort Study

To assess the association between glucagon-like peptide 1 receptor agonist (GLP-1RA) use and risk of incident thyroid tumors.

The retrospective, active-comparator new-user cohort study used international administrative claims and electronic health record databases. Participants included patients with type 2 diabetes mellitus (T2DM) with prior metformin therapy initiating a GLP-1RA versus new users of sodium-glucose cotransporter 2 inhibitors (SGLT2is), dipeptidyl peptidase 4 inhibitors (DPP-4is), and sulfonylureas (SUs). The outcome was incident thyroid tumor and thyroid malignancy. Propensity score matching and stratification were used to adjust for confounders with an intention-to-treat and on-treatment strategy. Cox regression was used to estimate hazard ratios (HRs) pooled using a random-effects meta-analysis. Unmeasured confounding was evaluated using negative outcomes, with calibration of the HR.

A total of 460,032 users of GLP-1RAs, 717,792 users of SGLT2is, 2,055,583 users of DPP-4is, and 1,119,868 users of SUs were included. Only U.S. cohorts passed study diagnostics. Thyroid tumor incidence ranged from 0.88 to 1.03 per 1,000 person-years in GLP-1RA cohorts. GLP-1RA exposure was not associated with an increased risk of thyroid tumors compared with SGLT2is, DPP-4is, or SUs (meta-analysis: GLP-1RA vs. SGLT2i HR range from 0.83 [95% CI 0.57-1.27] to 0.95 [0.85-1.06]; GLP-1RA vs. SU HR range from 0.95 [0.75-1.20] to 1.03 [0.87-1.23]; GLP-1RA vs. DPP-4i HR range from 0.78 [0.60-1.01] to 0.93 [0.83-1.04]). Analysis using thyroid malignancy and including a 1-year lag period produced similar conclusions.

In patients with T2DM initiating second-line treatments, we observed no increased risk of thyroid tumors with GLP-1RA exposure.